primer brand and Lee primer seating tool

  • Last Post 06 May 2019
loophole posted this 04 May 2019

I have used Lee primer seating tools for years, and never found this in the paperwork which comes with the tool.  The other day I read Lee's reloading manual and found that he warns users of the tool to limit the number of certain brands of primer loaded in the tray, while he states that filling it up with other brands is OK.  I suppose he is warning that primers may explode when used in the tray and that certain brands are seceptible to a chain reaction?  Have any of you any explanation of this? Would it apply to other brands of primer seater?


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RicinYakima posted this 04 May 2019

I remember this being for Federal standard primers?. They have the softest cups and most sensitive priming compound. If one got hung up halfway on the plunger and he-man crushed the primer, it could go off. Never knew of anyone who had this problem.

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RicinYakima posted this 04 May 2019

loophole, I think it applies to any tool or machine that has a magazine of primers and you can not see the primer enter the pocket. Like Star, Dillion, Hornady, Lee, etc.

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Ross Smith posted this 05 May 2019

I've read about the Lee tool. In my experience, you can crush the daylights out of a primer and no ignition. Tap it and it will go off. Has anybody had first hand bad experience here?

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lotech posted this 05 May 2019

Lee did some testing quite a few years ago regarding this. The results were written up in at least one gun publication. As I recall, they suggested using only CCI and Winchester primers in their priming tool magazine.  

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Eutectic posted this 05 May 2019

Chain fire can happen with any primer brand. Never ever store primers in bulk, keep them in the original packages. 

I tested primers many years ago. Federal primers are different, they use a different compound and are very quick in their ignition cycle and sympathetic ignition is much faster. The packaging of Federal primers reflects this, the box is four time the size of other primer boxes to keep the primers far apart. 

A magazine explosion with Federal primers will be more violent. However, a full magazine explosion of ANY primer brand is going to be bad. You should be wearing safety goggles! 

Putting only 10 or 20 primers in the tray at a time will limit the danger.



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Wineman posted this 05 May 2019

I always follow Lee' advice. I was helping a friend with his 338 win mag and he had a batch of WLRM (20 primers in the tray). I started priming the first case and wow, these are really, really hard to seat. After my buddy's WTF look I discovered that I had seated the first one (and my first with this hand prime tool) sideways. Primer went in and of course it too far out of the case to get it out of the shell holder. Had to use a de-priming rod from a Lee Loader after some careful disassembly. He had Federals too and I said that with my seater they were not recommended. Glad I stuck to the rules.


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John Alexander posted this 05 May 2019

As I remember Lee's old round magazine seater had the warning about primer make. When I bought the next generation seater(square magazine) it not only didn't have the warning but said because of the new design that somewhat separated the primer being pressed from the magazine it would take all brands of primer. I think that it the reason I bought it. The newer still (triangular magazine Lee seater doesn't have a warning that I can see.

Eutectic's warning still makes sense.


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tony1960 posted this 05 May 2019

I've had primers flip sideways and managed to crush them flat with no ignition, all of my primers are seated so the anvil leaves a dimple on the cup and have never had an ignition. 99% of my loading is Federal SP

A good friend of mine was filling up a primer tube on hid progressive press, as the primers hit the bottom of the tube one of them detonated and set the whole 100 off, nice hole in his ceiling and the seat of his pants, once again Federal primers.

I have set a primer off when seating it, scared the life out of me, but considering the hundreds of thousands I have loaded it was just bad luck.

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Glenn R. Latham posted this 05 May 2019

Lee's test that lead to their primer brand warning was interesting; they set a tray of primers on a hot plate and cooked them off.  Being an ornery cuss I decided if I didn't set my Auto Prime on a hot plate I was OK with any brand....


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Brodie posted this 06 May 2019


That reminds me of the early testing to see if marijuana was harmful to the mammalian nervous system.  First mice were fed Marijuana, then their brains were removed, homogenized, treated with 12 molar nitric acid, dehydrated and embedded in paraffin.  The tissue was sectioned and stained and examined under a microscope.  Of course the brain tissue showed enormous amounts of damage, not from the Mary Jane, but from the prep.

I suspect that what Lee was trying to find out was if there were any chain fires when one primer went off.  I guess they could of set a single primer off by means of a gas torch, but I guess a hot plate worked just as well.


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